TI recommends using ceramic capacitors with low ESR values to provide the lowest output voltage ripple. The output capacitor requires either an X7R or an X5R dielectric. Capacitors with Y5V or Z5U dielectrics display a wide variation in capacitance over temperature and become resistive at high frequencies.

At light load currents, the controller operates in PFM mode, and the output voltage ripple is dependent on the output-capacitor value and the PFM peak inductor current. Higher output-capacitor values minimize the voltage ripple in PFM mode. To achieve specified regulation performance and low output voltage ripple, the DC-bias characteristic of ceramic capacitors must be considered. The effective capacitance of ceramic capacitors drops with increasing DC bias voltage.

For the output capacitors of the BUCK controllers, TI recommends placing small ceramic capacitors between the inductor and load with many vias to the PGND plane. This solution typically provides the smallest and lowest cost solution available for DCAP2 controllers.

To meet the transient specifications, the output capacitance must equal or exceed the minimum capacitance listed in the electrical characteristics table for BUCK1, BUCK2, and BUCK6 (assuming quality layout techniques are followed). See Section 6.7, Electrical Characteristics: Buck Controllers.